I have been constructing a hobby room in my attic and discovered a pink foam that holds promise for modelling. It is made by Owens-Corning and is 1/4 inch thick and very light and stiff and used for insulation (R=1). It comes in fan-fold format and is four feet by fifty feet (4' x 50') for approximately $25 at Home Depot and Lowes. That's 200 sf at 12.5 cents per square foot! The folds are every two feet (2'), so there are uniform panels that are two feet by four feet (2' x 4'). Looks ideal for tail feathers, body parts and ribs. Not sure about wings.

I've just started using this material but for wings only. I've got a DMA Butterfly/Fundango clone flying using one of these wings, and am in the process of making an aerobatic wing for my T52. Both wings have a symmetrical airfoil.

The material can be tricky to form. I've generated a lot of scrap. The best technique I've found so far is to roll a crease where the leading edge will be. This crease must be as deep as possible, but if the foam cracks during this step - start over. I originally tried a roller for screen spline but this always cracked the foam. I now use a glass lid from a baking bowl. Makes a crease about 1/8" wide.

Once you've got a good crease, play a hot air gun on the opposite side while applying gentle pressure to gradually form a bend. You need to get the material hot enough so that the surface actually melts. You'll see it turn shiny. Watch those fumes though - they're nasty. I use a respirator and also have lots of ventilation. Continue heating and folding until you're past 90°. I quit when I've got a 60° angle.

I then use a household iron to form the gluing surface for the trailing edge. I set mine at 5 1/2 (the scale goes up to 7). Put wax paper on the foam. Hold the iron at an angle and glide back and forth until the correct width and angle is melted into the foam. Do this to both surfaces. The wax paper will stick - I end up sanding it off.

I temporarily install the spar (balsa) and glue the trailing edges together with Probond polyurethane (watch out for warps!). Once this has set, I clamp the wing chordwise using bar clamps and 2 x 4's to open up the wing so I can remove the spar. I then coat the spar with glue, slide it in place, and unclamp the wing.

My leading edges have not turned out perfectly straight. There is some waviness that I believe is caused by variations in the density of the foam. They seem to average out, and on the one wing that I have flying has not caused any problems. I'm flying this wing without any covering or additional reinforcement.

I've been able to heat form foamboard (w/o the paper), by putting the material over a 'mold' (another wing), and steel bars on the leading and trailing edges. You need to be careful with the application of the heat, but the foam does stretch and retains the form of the mold after cooling down.

Originally posted by Pierre Audette:I've been able to heat form foamboard (w/o the paper), by putting the material over a 'mold' (another wing), and steel bars on the leading and trailing edges. You need to be careful with the application of the heat, but the foam does stretch and retains the form of the mold after cooling down.

Pierre
What do you use for heating the foamboard?
After forming, do you end up with top and bottom surfaces that are glued together along with a spar for the finished wing?

I've also made closed wings with a 'C' shape spar, 1/8" balsa doubled up with 1/8" square sticks, to spread out the contact area on the foam. The leading & trailing edges sanded on an angle to glue them down on a wider area.

Had the opportunity last evening to play with this pink foam. It looks perfect for ribs. It is stiff. It is very easy to cut with a sharp knife or razor blade. It carves nicely and sands well. It weighs 1 oz per square foot. Have not tried to glue it, but I would guess any adhesive for other foam would be OK.

Found an adhesive at the craft store which I plan to try; it is called "Hold the Foam!" by Beacon Chemical Co. and is claimed to be a 'glue for styrofoam'. Works well on the Lite Stik foam. It is slow drying at about 45 minutes and is strong. Mine came in a 2 oz tube. Works also with wood, paper, cardboard and fabric.

Originally posted by realglow it is called "Hold the Foam!" by Beacon Chemical Co. and is claimed to be a 'glue for styrofoam'.

I just bought some too. Because its water based, I'm dubious how well it will do in holding large pieces together where air can't get to the joint. Most of these PVA esters don't dry when enclosed. For Lite Stik use it looks good.
Hoppy has reported on a bunch of them (Aleene's Fabric Glue I remember). One thing to watch is that the Beacon adhesive will re-soften in water even after drying.

Hint for bending foam. Before trying to bend the leading edge, put a strip of 2" masking tape over the leading edge. This will help to prevent it from breaking when you bend it. The other method is to cut the foam along the leading edge and than glue it together at a 90 deg angle. Once again, put some 2" wide tape on the outside of the leading edge before trying to bend it.
This works well with depron, maybe it will work with the material you have.

The newest material I'm trying now (which is not new to many people), is to cover the foam with Tyvec, the house wrapping material. It has fibers in it and is almost impossible to tear by hand. Glues very well to foam with Elmers white glue, does NOT shrink on drying, and looks like it should accept paint very well. It will not however stretch over compound curves like brown paper and white glue.
hoppy

Most users of this and the blue foam use Probond glue. It makes a very good bond, but you must be careful not to use too much, or it will foam up and ooze out of cracks and joints. The foaming action is good, however, for filling up those less-than-optimum joints.

Users of the blue foam claim it's stiffer than the pink stuff, because it has a clear covering on both faces, which the pink does not. You pays yer munny...